The map is a map of all the nodes which have either an amenity or shop
key in their tags. This is a good approximation of all POIs in an area,
which in itself is a good aproximation of how well mapped an areas is in
Data collection of this sort helps in a variety of ways. Firstly, it
makes OSM more useful as a general purpose map by placing shops and
restaurants on the map.
POI collection also helps with the often mentioned address issue. The
more POIs that are collected with full addresses, the better the
geocoder can be at determining where other objects are in relation to
that object. In other words, the more POIs you enter with addresses, the
more accurate OSM becomes in general about address data.
For me, this map is a useful visualization of where the map could use
some love. The city should be pretty dense with POIs except for green
spaces and some more residential neighborhoods in the outer boroughs.
For POIs, you have to go out and do on the ground surveying. You can't
capture the names of stores, types of restaurants, or addresses from
aerial imagery (at least unclassified aerial imagery).
If you aren't sure how to do good POI collection, we'll be doing this at
the mapping party, so you'll be able to do it by the end of that. If
that's not soon enough, maybe we can talk about POI collection at the
next virtual meeting this week.